Automatic valve means



Feb. 2, 1954 T. HOFFACKER, JR

AUTOMATIC VALVE MEANS Original Filed April 5, 1947 Fig. l

CO-PILOT 92C 6 86 9 INVENTOR; Theodore Hof er ATTORNEY pump I in the event any excessive pressure is developed within the line I0, or that portion of the system to which it is connected. The main pressure supply line is indicated at I2 from which it branches to the left and to the right into the branch pressure lines I3 and I4. As the fluid pressure enters each of these branch lines, it passes through the check valves I5 and Con- 23, and a similar accumulator 22 and pressure" gauge 24 is connected to the branch pressure line I4.

As the left branch pressure line continues, it branches at the cross connection 25 into the further pressure lines 21, 29 and SI which communicate with the set of operating Valves on the left or pilots side of the airplane. As the right branch pressure line continues, it also separates at the cross-fitting 25 into the further pressure lines 28, 30 and 32 which communicate with the set of operating valves on the right or co-pilots side of the airplane. From the cross-fitting in the pressure line I 3 at the left side of the airplane a pressure branch 33 extends across to the right side of the airplane, and similarly a pressure line 34 from the fitting 23 in the pressure line l4 on the right side of the airplane extends across to the left side of the airplane.

The pilots position on the left side is provided with a pair of pedal actuated brake valve assemblies 35 and 3'! which receive their fluid pressure through the above mentioned lines 21 and 3 5, respectively, and the co-pilots position on the right side of the airplane'is provided with similar brake valve assemblies 33 and 38 which receive their fluid pressure through the lines 32 and 28, respectively. The brake valves 35, 33, 3! and 33 are each identical and will be more fully explained in connection with the detailed showing of the valve 35 in Figure 3. Each of these valves is provided with connections to the wheel brakes through the lines 39, 43, AI and 42, respectively, through the interconnector and equalizer valves 43 and 44 which are more fully shown in detail in Figure 2. The brake valves 35, 36, 31 and 38 are provided with connections to the main return line I9 by way of the branch lines 45, 45, 4! and 48, respectively, the latter three lines being connected into the return header 49 to join the main return line I9 at its junction with the branch return 45 from the valve 35.

The airplane to which the present brake system is shown and described as being applied is preferably provided with a pair of laterally disposed landing wheels each of which is provided with inboard and outboard wheel brake units. The left interconnector and equalizer valve '43 is provided with an outlet 85 in communication with the fluid line 5| to the outboard wheel brake unit 55 of the left landing gear wheel 59. Similarly there is provided an adjacent outlet 86, in the interconnector and equalizer valve 43, for communication through the line 53 with the inboard wheel brake unit 5? of the same left wheel 53. The right interconnector and equalizer valve A i is similarly provided with adjacent outlets and communication through the lines 52 and 54 with the outboard and inboard wheel brake units 56 and 53, respectively, of the landing gear wheel 60 on the right side of the airplane.

Referring now to Figure 3, the numeral 35 indicates the pedalactuatedbrake valve 35 shown in the diagram in Figure' 1,which valve is also identical with the brake valves 35, 3? and 38.

This brake valve, which is shown schematically in this figure may preferably be of the type shown and described in Patent No. 2,397,234 to J. R. Blake which issued March 26, 1946. The valve comprises essentially a substantially cylindrical body or housing portion 6I having a straight bore 62 of uniform diameter throughout, and closed at the endsof the housing by suitable removable flanged caps, the fastening means for which have not been shown in this schematic cross-section. An internally screw threaded port 33 is provided for coupling the pressure line 21 to the valve, and similar ports 34 and 65 are provided for coupling the fiuid line 39 and the return line 55, respectively.

A pressure valve unit 63 is mounted for axial movement within the cylindrical body of the valve, being guided within the valve guide abutment portion 5i, which forms a pressure chamber 68 open to the pressure inlet port 33. The pressure valve unit 33 includes a piston stem portion 33 within the guide portion 61, which guide portion is provided with ports It serving to provide communication between the pressure chamber 68 and the chamber II which is open to the brake actuating line 35 through the threaded port 64. A piston-valve unit 63 is reciprocally mounted Within the bore 62, having a long skirt or guide portion 75 at its farther end to form an intermediate chamber I6 open to the return port 35 and the return line 45. The adjacent end of the stem 39 is adapted to form, in cooperation with the adjacent end of the piston portion 73, a return valve unit I2 which is urged into its normal position by the compression spring I4 interposed between the abutment portion 57, and the piston portion I3. Within the skirt portion I5 at the other end of the reciprocable piston-valve, there is interposed a further compression spring 11 between the pistonvalve unit and the keeper I8.

The piston-valve assembly 73 is also provided with a central bore or passage 33 which allows fluid communication between the chamber II and the chamber within the skirt portion 25, and the transverse branches 8| provide communication between the central bore and the return chamber 16. A plunger or stem I9 is guidingly mounted for axial reciprocation through the end wall of the cylindrical. body BI, bearing against the keeper I8. This plunger is arranged to transmit braking forces from the operators foot, through suitable pedal mechanism, against the keeper I8, the compression spring fl, and the elements comprising the brake valve assembly 35. It will be understood that suitable packing rings or seals are preferably disposed at each of the surfaces between the relatively moving parts of the present valve assembly in order to provide a fluid-tight arrangement, and that these seals have necessarily been omitted from the schematic showing in Figure 3 for purposes of clarity.

Referring now to Figure 2, there is shown an enlarged cross-section of the interconnector and equalizer valve assembly 43 on the left or pilots side of the airplane, which assembly is identical in construction with the counterpart 44 on the right, or co-pilotfis side of;the airplane. The valve assembly. 43 comprises :a cylindrical. body; portion 82 in which there.hasbeeneintegrally formed. the internally threaded ports. 83,. 8.4, 85 and; 8.5, adapted to be connected to the lines 39;, 41!, 5| and 53, respectively. It will: be noted from; Figure-1, that the line 99 communicates. with. the brake valve 35 on the left side of the airplane and'that the line 49 communicates with the: brake valve 36 on the right side of the airplane. The lines 5| and 53, communicate with the outboard, and inboard brake units 55 and 5.1', respectively, of? the left wheel 59. The body or-housing portion. 82 is provided with a centrally bored cylinder portion STI'Within whichthe primary. piston 88 isadapted toreciprocate in the axialdirectionofthecylinder. The piston 89 is provided with a suitable pressure seal 88: and divides-the centrally bored portion into the chambers 8.9.and290;

The body 82: of the valve assembly: is bored at each end to a slightly. larger diameter thanv that of the central bore 81', whichthe endbores'meet at the shoulders 91a and 81b. Valve guide portions 9| and 92 are disposed Withinthe enlarged diameter end portions of the. body 82, being retained therein by. the threaded: end cap. portions 93 and 94, respectively; The central piston 88 is provided with. axially extending rodportions having valves 88b and 890 formed at each end. The. valve guide. portion9| has. a tapered spider portion 9|a extending into the-chamber 89 adapted to guide the piston valve end 88b and the corresponding valve guide-element 92 has a like. portion 92a for. guiding the valve end 880. The valveguide element 9| is bored for the reception of a reciprocable valve-member 95, and its counterpart, the valve guide element 92 has a similar internally bored portion for receiving the reciprooable valve element 96. The-end cap portion 93 is arranged tohousea spring loaded ball valve 91 in conjunction with the terminal fitting 97b and the interposed spring- 91a. Similarly the end cap 99 houses the spring loaded ball valve 98 in cooperation with theterminal fitting 98b and the interposedspring 98a.

The terminal fittings 97b and 98b are-suitably threaded to engage the end-caps93 and94', havingshouldered portions by which they may be tightened against the end caps and are provided with threaded terminals for engagement with the pressure lines 29 and 34, respectively. Radially disposed passages 9|b are provided within the guide element9| to provide communication between the centralchamber portion- 89-and the port 83 when the valve 8% is in the openposition; and the guideelement 92' is similarlyprovided with radial passages 92b toprovide similar communication between-the chamber 99 and-the port 84 when the corresponding-valve element 88c-is in the open condition. The valveguide elements 9| and 92 have their internally bored portions shoulderedto lim-itthe inward position ofthe reciprocable valves 95 and 96; which-- areurged thereinto by the compressionsprings 95a-and- 96a. The guide element 9|and the'endcap 93 are adapted to form betweenthem-theend chamber 99 which is in communication with the central chamber Baby means of the communicatingpassages 9 0 extending longitudinallythrough the. Similarly the guide elementnationjot Figure. 2;v that? the; primary pi'storr'88 and its valve portions. bland; 88c guided'zby the: portions. 9.1a and? 9200;, respectively, arev free to move, either to the left,.or: to the; right as the case maybe. The sliding valves 9.5; and. 96;retained; by the guide elements 9| andz9-2; respectively, are urged by the springs a; and; 9.6a; into their positionsof closestnapproach; in which they. bear against the shouldered; portions ofthe bores of the guide elements. 91 and 92Lbuti in which they. each fallshortof closing the'valves formed by. the piston portions98b. and. 880. 0p.- posite or outwardmovement; of! the valves 95 and 96, however, within: the limits of their motion and by compression of? their respective springs 95a and 96d, canunseatthe-ball? valves 9] and 98; They arelimited. in such outward movement, by contact withl the stop portions 93a and 94a on theresp'ectiveendi capfittings. The central chambers 89 and" 9|)w extend through the valve guide elements 9| and92, respectively-into the chambers 99 and I99, as described-above,- by virtue of the passages 9 c-and 920. As also-in--v dicated above, the port 83 -isplacedin communi cation with the central-chamber 89 by-the-radial passageways 9|b, as controlled by theva-lvetflb; and similarly the port 84 isplacedin communication. with the central chamber-99 -bythe radial passages 92!) as they may becontrolledby the valve 890. Similarly the pressure lines: 29':- and 34 are axially disposed at the oppositeendsof the interconnector and equalizer: valve 43" and are closed off from their respectivechambers- 89-99 and 99|90 by means of the-springloaded ball valves 97 and'99, respectively. As the case of the brake valve schematically shownand described in connection with-Figure 3,- eachof-the relatively moving or movable" elements of the present valve are also provided with pressure seals to prevent leakageof fluid at-.e1evated pressures between these elements, or-past the respective valve units.

As indicated in Figure 'l, twoassembliesof'the interconnector and equalizer valves, name1'y-assemblies 43 and 44, areirequ-ired for-each dual installation. One valve assembly, namely,- 4-3, is connected to the pilots left foot brake-valve 35 by the line-39 and'the'same assembly 43- is also connected to the co-pilots left foot brake valve 33 through the line iti The line 39--fromthe pilot's leftfoot brake valve 35-is capableof-communication with the outboardleft 'w-heel; brake unit- 55 through the line- 5| as controlled by'the left side of the assembly; and the line 49 -f-rom-the-copilot's left foot brake valve-36-is capable of being placed in communication witntheinboard wheel brake unit 57 of the left-wheel 59- by means of the line 53 as controlled by the right sideof' the assembly 43; Similarlythe-right-wheel fiilisgsubject to brake control from 'thepilots and copilots right foot'brake valves 3'|=and=-38, through the lines 4| and '42, respectively; which are capable of being-placed in communication with the lines 52 and 59, upon proper-actuation of the in: terconnector and equalizerassembly 44 for-thecontrol of the outboard andtheinboard wheel brake units 59 and 58; respectively; of" the-rightwheelfifl.

The description of-' the operatioi-i of'the dual brake system shown'in Figural; embodying the valve assemblies shown-in detail in'Figures 2";and 3; involve the four principalstagesof a-complete cycle of'operation, namely: (1) Brakes'ofij (2)" brakes: being applied; (3)- brakes applied and pressure-equalized; and tei brakes being 'releasedz" 7 "In the first stageof operation, namely, the brakes off condition, let us assume that the system shown in Figure 1 has been filled with an adequate supply of brake fluid throughout all portions of the system and to the required level within the reservoir 5. The pump 1 i driven from a suitable power source, drawing fluid through the line 6 into and through the filter 8, past the check valve 9 and into the main pressure line i2, from which it branches through [3 and 14 into the left and right halves of the system, respectively. In branching into the twohalves of the system the fluid passes through the respective check valves and [6, past those portions of these pressure lines which are open to the accumulators 2| and 22. The latter serve to accumulate and build up a reserve pressure on the 7 work side of each accumulator, which pressure is indicated by the pressure gauges 23 and 24, respectively. The pressure switch H at the end of the branch line 10 provides an unloading feature by disconnection of the power source of the pump 1 upon the creation of excessive pressures. A further relief from pressures in excess of a predetermined magnitude is provided by the pressure relief valve l1 past which the fluid is returned through the relief line land the return line to the reservoir 5, as previously described, to relieve the system of such excess pressures. Accordingly, with the pump runnin and the full pressure upon the system and without braking forces applied to the pedal plungers 19 of the brake valves 35. 36, 31 and 38, the full pressure will be built up within the pressure chambers 58 of each brake valve as the fluid is transmitted through the pressure branches 21, 28, 3| and 32. In this condition of the system the pressure valve unit 65 of the brake valve 35 (as well as that of the'remaining brake valves 36, 31 and 38) will be in the closed position due to the influence of the spring 66a, assisted by the pressure within the line 21 (and the corresponding branches 28, 3| and 32 to the remaining brake valves), and the piston valve 12 will be open due to the influence of the spring moving the piston assembly 13 toward the end of the bore 62 at which it overcomes the lack of brake force on the plunger 19. places the relief line 18 as well as all of the return portions of the system under atmospheric pressure, and inasmuch as each of the brake valveS has its pressure valve unit closed, and its piston valve open, the lines 45-39, 41--4 I, 46-40 and 4842 will be open to each other; and accordingly the lines 39, 40, 41 and 42 will also be atatmospheric pressure.

' Referring now to Figure 2, inasmuch as the lines 39 and 40 connected to ports 83 and 84, respectively, are under atmospheric pressure, the piston 88 will be in its normal central position at which the valves 88b and 880 will be open and the pressure within the chambers 89 and 99 through the passages Bio, and that within the chambers 90 and I00 through the passages 920, will also be equal and at atmospheric pressure. The pressure lines 29 and 34 connected to the opposite ends of the assembly 43 are, however, open to the main pressure line [2, and its branches [3 and I4, and the valves 91 and 98 will be closed by their respective springs against the pressure within the system (which might preferably be of the order of one thousand pounds per square inch). The fluid at the terminal connections at the closed ball valves 9101 the assemblies 43 and 44 is accordingly under a pressure of about 1000 p, s. i,,

an .z le squree' hr u h, the newer br I and the line'szs'a'nd' '33 to the assemblies 43 and 44. The further lines 5| and 62 control the outboard brake units 55 and 56, or the outboard portion of the brake hydraulic system. The fluid at the opposite ball valves 98 is also under a like pressure of about 1000 p. s. i., but its source is through the pressure branch 1 4 and the branches 34 and 30, which through the respective assemblies 43 and 44 and the further lines 53 and 54 control the inboard brake units 51 and 58, or the inboard portion of the brake hydraulic system. Accordingly, in addition to the relief and return lines, each of the brake valves 35, 36, 31 and 38 is under atmospheric pressure except for their pressure chamber portions up to the pressure valves 65; and the lines 39 and 40 through the central portion of the valve assembly 43, to the brake units 55 and 51, are also under atmospheric pressure. Similarly the lines 4| and 42, and the central chamber portions of the valve assembly 44, through to the brake units 56 and 58, are also under atmospheric pressure and the brake units 55, 56, 51 and 55 accordingly are each in the brakes-off condition.

The operation of the system and its parts for the second stage, namely, brakes being applied, is as follows: Let us assume that the pilot applies the brakes in his portion of the system by exerting braking forces upon the pedal plungers 19 of the brake valve 35 and 31 on his, or the left side of the airplane. This movement of the plunger 19 initially closes the valve 12 thereby closing off the operating line 39 from the return line 45 and the corresponding operating line 4| from its return line 41. .Further movement of the plunger 19 and the piston 13 opens the pressure valve 56, subjecting the line 39 to a braking pressure. Chambers 89 and 98 at the left side of each interconneotor and equalizer valve assembly 43 and 44 are accordingly subjected to the braking pressures corresponding to that which is passed by the respective brake. valves 35 and 31. Since the primary piston 88 is unrestrained, and the chamber 90 is at atmospheric pressure and appreciably below that in the chamber 89, it is obvious that the piston must move to the right, or in the direction of chamber 90, thereby closing the passage between chamber 90 and passage 92b by the closing of the valve 88c. A similar operation obviously will occur in assembly 44. As the braking pressure continues to be applied and is increased in magnitude, the primary piston 38 continues to move toward the right in each of the assemblies 43 and 44, moving the sliding valve unit 96 along with it toward the right, which action in turn causes the small valve 98 to be unseated and opened, thus permitting high pressure fluid to enter the chamber I00 and to be directed out through the port 86 of each assembly 43 and 44, and thereby into the lines 53 and 54 connected to the inboard brake units of each wheel, or the inboard brake system. During this continued movement of the piston 88, the sliding valve unit maintains the closed condition of the valve 080, thereby preventing fluid pressure flow back into the line 40.

. The condition of the entire system and its parts for the third condition, namely, brakes applied and pressure equalized, is as follows: Continued application of, pedal braking forces to the brake valves 35 and 31 consequently maintains the valves 66 in the open position and the valves 12 in the closed position, permitting continuation of fluid pressure flow through the ball valves, ofeach assembly ,43 and 44,.such that 9 the pressure on both sides of the primary piston 88 gradually becomes equalized at the brake operating pressure. This also means that the pressure in the brake line 53 connected to the port 85 is now equal to the pressure in the brake line.

5| connected tothe port '85, and these pressures are also equal to those in the brake lines 52 and 54, assuming equal pressures applied to the pedal plungers -19 of units 35 and 31. Ihis equalizing condition between the brake units of a given wheel exists by virtue of the fact that, as the pressure in chambers 90 increases due to fluid entering through the ball valves 98, the primary pistons 88 are forced to move to the left or toward the chambers 89, as the pressure in the chambers 90 becomes slightly greater than that in chambers 89. The ball valves 98 close due to the concurrent movement of the pistons 88 and valve elements 96, thus preventing any further increase in pressure. As the sliding valve elements 98 again reach their normal positions the continued piston movement opens the valves 880. The slightly greater pressure in chambers 90, which is required to move the primary pistons 88, is relieved through the passageways 92b, past the now open valves 880 into the line 40 (and 42), each of which is under atmospheric pressure. This results from the continued movement of primary pistons 88 in the direction of chambers 39 and the opening of valves 880 creating communication between chambers 99 and the passages 92b. As soon as this excess pressure is relieved, the relief action discontinues and the passages 9% are again closed by the valves 880 by virtue of the position of the pistons 88 which are not as yet in their central positions but are still displaced toward the right, or chambers 95. The brake line pressures at the ports 85 and 86 are thus equalized, thereby equalizing the pressures within the brake lines 5| and 53, and the braking pressures applied at the brake units '55 and 51, as well as at the brake units 56 and 58 of the other wheel. It will be understood that similar actuation of the brakes can be accomplished by the co-pilot by similar application of braking forces upon his brake valves 36 and 38 on the right side of the airplane with the balancing of the brake line pressures accomplished by similar but opposite movement of the primary pistons 88 in each of the interconnector and equalizer assemblies 43 and 44.

The operation of the system and its parts under the fourth, or brakes being released condition, is as follows: As the force exerted by the pilots feet against the plungers 19 of the valves 35 and 3! is released the piston portions 13 f the brake valves 35 and 3? follow the outwardly moving plungers 19 to the left carrying with them the pressure valve assemblies 56 and 12 (the valves F2 closing first and remaining closed temporarily), and the valves 66 subsequently closing off the fluid pressure after suificient piston movement has taken place. pressure initially applied through the lines 39 and 4! to the ports- 830f the valves 43 and 44 is accordingly cut oii from lines -21 and '31, and the fluid from the brake lines 5! and 52 connected to the ports 85 passes into the chambers 89, past the open valves 88?), through the passageways 9i?) and into the lines 39 and 4!. As the plungers Til reced'e further from the interior of the brake valves 35 and. 31, the piston units =13 continue movement past the point where the valves 12 again open, some time after the closing of the pressure valves 66, and the lines 39 and M The braking,

then become open through the ports 64, past the open valves 12 and the passages and 81-, into the return line 45 and '41 through the ports 65. This permits the braking pressure initially applied to the brake lines 5| and 52 to pass through the interconnector and equalizer valve assemblies 43 and 44, and the brake valves 35 and 31, and to be returned to the hydraulic reservoir 5 through the return lines 45, I9 and 2 0, respectively. Simultaneously with the reduction of pressure in the chambers 89 by fluid returning to the reservoir 5, communication between the passageways 92b and the chambers 90, past the valves 880, is opened due to the further movement of the primary pistons 88 in the'direction of chambers 89, caused by the differential pressure between chambers 89 and 90. The brake line pressure at the ports 86 through the brake lines 53 and 54 then is relieved and hydrauli'c fluid from the brake units 51 and 58 return to the rese'rvoir5 by way of the lines 53, and 54, the ports 56, the chambers 99, past the valves 880, through the passageways 92b and the lines 40, and 42 through the brake valves 36 and 38, the return branches 46 and 48, the return header 49 and the main return line 19-20. With the release of the brakes and the return of the pistons t8 and all of the remaining elements to their neutral positions, as has just been described, one full cycle of operation has been completed, and the system has again returned to the original static stage as described in the first, or brakes off, condition.

It will, accordingly, be seen that a dual braking arrangement has been provided in which independent operation of-either the inboard-or entboard brake system is possible, in the event of the failure of either one of these systems. Inasmuch as each operator station is supplied by a separate pressure line and controls either the inboard or outboard systems having a brake unit on each wheel, either system can be operated independently of the other, should failure occur in the other system. It will also be noted that the full braking capacity of both the inboard and outboard brake systems is available to, and can be applied by either the pilot, or the co-pilot, or both. It will also be observed that these functions and operations are accomplished without the necessity of any mechanical linkage connecting the pilot and co-pilot brake pedals, which thereby eliminates design complications and critical adjustments heretofore required by such linkages. To dispense with these mechanical linkages further eliminates a source of possible diiiiculty and cause of failure of the entire system. The provision of the novel automatic switching or interconnector and equalizer assembly makes it possible to provide a smoother and more gradual application of the brakes than has heretofore been possible in similar systems. This improved application is due primarily to the differential action of relatively small magnitude resulting from the operation of this equalizer unit. More particularly, and to further clarify this aspect of the invention, the inboard brakes will lead the outboard brakes slightly, or vice versa, depending upon whether the pilot or co-pilot operates the brakes, before equalization of the pressure occurs. This condition results from the fact that one of the systems is operated directly by actuation of the brake valve, while the other system is operated indirectly by the equalizer valve as a secondary reaction to the introduction of pressure in the first :system.

It will be understood that the above described modification is but one of many forms which the present invention may take. For example, while the pilot initially controls the outboard brake units of each wheel and the co-pilot controls the inboard brake units, equally eflective results may be obtained where the arrangement is reversed, namely, where the pilot controls the inboard, and the co-pilot controls the outboard brake units. It is common practice in large aircraft to provide dual or double wheel landing gear units and the improved brake system is equally applicable to such landing gears regardless of the number of wheels, or the number of brake units per wheel. The system can also be arranged for use on a single wheel controlled from two separate stations, or for the simultaneous actuation of the landing flaps from either station. While two brake units have been shown and described for each wheel, obviously the invention is applicable to a greater number per wheel as well as to a vehicle having any number of wheels arranged for braking. It will also be apparent that either operator can brake the wheels with difierent braking force and when the other half of the system is brought into action the equalization is made only between the units of a given wheel, and not as between the several wheels. The equalization of pressures by the equalizer valve will be as complete as may be obtained in accurately fitting hydraulic equipment of the present type. Accordingly, with due allowance for friction, seals, inertia, etc., the use of the term equalization in any of its forms herein will be understood to mean that the pressures will be substantially equalized.

It will, of course, be obvious that the improved valve means has been shown and described in conjunction with a wheel brake system for explanatory reasons only, and that it is not limited to use therewith but enjoys general application in other fluid systems.

Other forms and modifications of the present invention, Which will occur to those skilled in the art after reading the foregoing description, are intended to fall within the scope and spirit of this invention as more particularly set forth in the appended claims.

I claim:

1. Automatic valve means comprising a cylinder a double-acting piston reciprocable within said cylinder, first and second piston-valves operatively associated with said piston, a normally open fluid inlet connection to said cylinder on each side of said piston, a normally closed pressure connection to said cylinder on each side of said piston, a valve operatively associated with each said pressure connection, said cylinder having an outlet connection on each side of said piston, each said piston-valve disposed such that it controls fluid flow from said inlet connection to said outlet connection on its respective side of said double-acting piston, a valve actuator element on each side of and movable with said piston arranged upon increased fluid pressure within the inlet and outlet connections on one side of said piston and displacement of said piston away from that side to close the pistonvalve on the opposite side of said piston and to actuate the valve operatively associated with the pressure connection on that side of the piston to thereby apply fluid pressure to the outlet connection on that side of the piston.

2..An automatic interconnecting and. equ l izing' valve comprising a cylinder, a double acting free piston reciprocable within said cylinder, first and second piston valves operatively associated with said piston, normally closed pressure connections on each side of said piston, a valve operatively associated with each said pressure connection, said cylinder having outlet ports on each side of said piston, said cylinder having inlet ports on each side of said piston,- a movable valve actuator element in said cylin der on each side of and cooperating With said piston arranged to cut-off the flow from thesaid inlet port to the outlet port on one side of said piston and to open the operatively asso-- ciated valve in the pressure connection on that side of the piston initiated by displacement of said piston toward that side upon increased pressure within the cylinder on the opposite side of said piston from said inlet port on that side to its respective outlet port.

3. An automatic valve comprising a body having a cylindrical bore forming a cylinder, a double-acting free piston reciprocable within the bore of said cylinder and dividing the same into fluid chambers, said valve body having a fluid inlet port and a fluid outlet port on each side of said piston, normally closed valved connections to the said cylinder on each side of said piston, and movable piston-valve elements reciprocably disposed within said cylinder on each side of said piston arranged to cooperate therewith to cut-off the flow from either one of said fluid inlet ports to its respective fluid outlet port upon displacement of said piston initiated by increase in the fluid pressure in the fluid chamber on the opposite side of said piston, said movable piston-valve elements arranged upon further displacement of said piston to open the valved connection on the side of the cylinder toward which the piston is displaced to permit fluid to enter said chamber portion.

4. An automatic valve comprising a bored body forming a cylinder, a double-acting free piston reciprocable within said cylinder and dividing the same into two fluid chambers, each said fluid chamber having a fluid inlet port and a fluid outlet port normally in communication in the neutral balancedcondition of the valve corresponding to a central position of said piston, a normally closed valved high pressure connection to each said fluid chamber, and slide valve elements within each said chamber on each side of said piston arranged to cooperate with said piston to cut-off the flow from one of said fluid inlet ports to its respective fluid outlet port upon displacement of said piston initiated by increase in the fluid pressure in the chamber on theopposite side of said piston, said slide valve elements arranged upon further displacement of said piston to open the valved connection on the side of the cylinder toward which the 'piston is displaced to permit high pressure fluid to enter said chamber portion.

5. An automatic valve comprising a bored body forming a cylinder, a double-acting unrestrained fluid-balanced piston reciprocable within said cylinder and dividing said cylinder into two fluid chambers, said valve body having an inlet port and an outlet port on each side of said piston for separate fluid flows through each said chamber, normally closed valved connections from a pressure source to each said fluid chamber, a movable slide valve element within each said fluid chamber on each side of said piston arranged 0 be actuated by said piston to cut-ofi the said fluid flow from either of said fluid inlet ports in one of said chambers upon displacement of said piston initiated by increase in the fluid pres-- sure in the fluid chamber on the opposite side of said piston, said movable slide valve element arranged upon further displacement of said piston to open the valved connection from said pressure source on the side of the cylinder toward which the piston valve is displaced to permit fluid from said pressure source to enter said chamber portion, and resilient means associated with said actuated slide valve arranged to maintain said fluid flow in its cut-off condition until after said opened valved connection from said pressure source is again closed.

6. Automatic valve means comprising a free piston reciprocable within a cylinder, said cylinder having fluid chambers on each side of said piston, each said fluid chamber having a fluid inlet, a fluid outlet and a normally closed pressure inlet, a slide valve on each side of and actuated by displacement of said piston, means including ports cooperating with each said slide valve effecting fluid interconnection between a first of said fluid inlets and its respective fluid outlet through a first of said chambers, means including valve elements carried on opposite sides of said piston for blocking said fluid interconnection in the other said chamber by the closing of its respective slide valve, and means carried by said closed slide valve for applying equalized hydraulic pressure from the other pressure inlet to the other said fluid outlet initiated by flow through the first said fluid inlet and disp1acement of said free piston.

7. An automatic interconnecting and equalizing valve for use in a dual hydraulic system comprising a cylinder, a double-acting free piston reciprocable within said cylinder, first and second piston valves operatively associated with said piston, normally closed pressure connections on each side of said piston, a self-closing valve operatively associated with each said pressure connection, said cylinder having outlet ports on each side of said piston, said cylinder having inlet ports on each side of said piston, a movable valve actuator element in said cylinder on each side of said piston arranged to actuate the piston valve to cut-off the flow from the said inlet port on a first side of said piston and to open the operatively associated valve in the pressure connection on that first side of the piston initiated by displacement of said piston toward that first side upon increased pressure within the cylinder on the opposite or second side of said piston from said inlet port on that second side, for automatic interconnection and actuation by separate pressure flows at substantially equalized pressures.

8. Automatic valve means comprising a fluid cylinder, a double-acting floating piston reciprocable within said cylinder, said piston dividing said cylinder into fluid chambers, a piston-valve disposed in each said chamber operatively associated with said cylinder and said piston, a normally open fluid inlet connection to each said chamber, a normally closed pressure connection to each said chamber, a self-closing valve operatively associated with each said pressure connection, each said chamber having an outlet connection to its respective pressure-actuated unit, a valve actuator means carried by said piston arranged upon increased fluid pressure within the inlet and outlet connections in one of said chambers and displacement of said piston away from that chamber to close the piston valve in the opposite chamber and to open the said selfclosing valve operatively associated with the pressure connection on that side of the piston to thereby apply fluid pressure to the outlet connection on that side of the piston and its respective pressure-actuated unit in such manner that said floating piston automatically equalizes the actuating pressures to both said units.

9. Automatic valve means comprising a cylinder, a free piston reciprocable within a central portion of said cylinder, a slide valve reciprocable within said cylinder on each side of and actuated by displacement of said piston, an inlet into said cylinder on each side of said piston, an outlet from said cylinder on each side of said piston, a

pressure connection on each side of said piston at each end of said cylinder, and means includr ing actuating portions carried by said piston cooperating with said slide valve for normally effecting fluid interconnection at low pressure across an end of said cylinder between a first of said inlets and its respective outlet, said means arranged upon increased pressure through said first inlet for applying equalized hydraulic pressure from the second said pressure connection at the opposite end of said cylinder to the second said outlet in the opposite end portion of said cylinder initiated by admission of increased pressure flow through the first said inlet and displacement of said free piston toward said opposite cylinder portion.

THEODORE HOFFACKER, J's.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,208,820 Tarris July 23, 1940 2,273,535 Peo Feb. 17, 1942 2,443,642 Rockwell June 22, 1948 2,467,560 Majneri Apr. 19, 1949 2,491,812 Hofiacker Dec. 20, 1949 2,526,570 Majneri Oct. 17, 1950 

